As a kind of semiconductor memory devices, a resistance change memory has been known. Further, as a kind of resistance change memories, an MRAM (magnetoresistive random access memory) has been known. The MRAM is a memory device in which a magnetoresistive element having a magnetoresistive effect is used in a memory cell storing information. MRAM writing scheme includes a spin-transfer torque writing method. In the spin-transfer torque writing method, the smaller the size of a magnetic body, the lower a spin-transfer current required for magnetization reversal, and therefore, the spin-transfer torque writing method is advantageous in high integration, small power consumption, and high performance.